The present invention relates to an autostereoscopic display apparatus comprising means for producing a display which comprises an array of display pixels arranged in rows and columns, and an array of elongate lenticular elements extending parallel to one another overlying the display pixel array and through which the display pixels are viewed.
Examples of such autostereoscopic display apparatus are described in the paper entitled "Multiview 3D-LCD" by C. van Berkel et al in SPIE Proceedings, Vol. 2653, 1996, pages 32-39, and in GB-A-2196166. In these apparatus, a matrix display device comprising a LC (liquid crystal) display panel having a row and column array of display elements and acting as a spatial light modulator produces the display. The lenticular elements are provided by a lenticular sheet, whose lenticules, comprising elongate (semi) cylindrical lens elements, extend in the column direction of the display panel, parallel to the display element columns, with each lenticule overlying a respective group of two, or more, adjacent columns of display elements. Commonly in such apparatus, the LC matrix display panel is of a conventional form, comprising regularly spaced rows and columns of display elements, as used in other types of display applications, e.g. computer display screens. In EP-A-0625861, further examples of autostereoscopic display apparatus are described which use LC matrix display panels having non-standard display element lay-outs in which adjacent display elements are arranged in groups with the display elements in a group being arranged so as to be substantially contiguous with one another in the row direction. There is also described in this specification an example of a projection apparatus using such panels in which an image of the display element array is projected magnified onto a screen and in which the lenticular sheet is associated with the screen.
Considering a direct-view type of apparatus, then the display pixels forming the display are constituted by the display elements of the display panel. In an arrangement in which, for example, each lenticule is associated with two columns of display elements, the display elements in each column provide a vertical slice of a respective 2D (sub-)image. The lenticular sheet directs these two slices and corresponding slices from the display element columns associated with the other lenticules, to the left and right eyes respectively of a viewer in front of the sheet so that the viewer perceives a single stereoscopic image. In other, multi-view, arrangements in which each lenticule is associated with a group of four or more adjacent display elements in the row direction and in which corresponding columns of display elements in each group are arranged appropriately to provide a vertical slice from a respective 2-D (sub-) image, then as a viewer's head is moved a series of successive, different, stereoscopic views are perceived creating, for example, a look-around impression. Similar stereoscopic effects are obtained with a projection apparatus except that in this case the display pixels forming the display, on the screen, are constituted by projected images of the display elements.
The use of a matrix display panel in conjunction with a lenticular screen whose lenticules extend parallel to the display element columns provides a simple and effective way of achieving a 3-D display. However, for a standard type of display panel having a given number of display elements in a row then in order to provide a plurality of views in the 3D display, horizontal display resolution is necessarily sacrificed. For example, with a display panel having an array of 800 columns and 600 rows of display elements (each of which display elements may comprise a colour triplet if a full colour display is required) then for a four view system providing three stereo pairs at a fixed viewing distance the resulting display would have a resolution of only 200 in the horizontal, row, direction and 600 in the vertical, column, direction for each view. Thus, the stereoscopic images as seen by the viewer each have a comparatively high vertical resolution but only a comparatively small horizontal resolution. The substantial difference between vertical and horizontal resolution capabilities is, of course, undesirable.